This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The objective of this study is to utilize the SIV/macaque model system to determine the pathogenesis of Bartonella infection in SIV-infected, immunocompromised macaques, and evaluate the SIV/macaque system as a potential model for BA. SIV-infected animals, at various stages of immunodeficiency, will be inoculated intradermally with B. henselae, B. bacilliformis, or B. quintana organisms, and monitored for onset, duration, immune response, and clinical outcome of bacteremia.